There are known and are commonly used for small flexible hoses male-female fittings wherein the male element is held by small radial pawls urged by elastic means interposed between an internal cylindrical part of the female and a sleeve which is axially slideable on said internal part.
For hoses having a large diameter (typically one inch), fittings having the same structural and operational characteristics of the fittings used for smaller diameter hoses (say, half an inch) there are several problems.
The first problem is the size of such fittings, which may make their use not all that easy.
There are also problems connected with the plastic material of which said fittings are made; if the thickness of the plastic is large it is necessary to use special dies and the cost of the material increases. If the thickness of the plastic remains small significant deformations may occur due to the lower resistance of the plastic; there are also dangers of breakage or of undesired clearances.
In addition the typical coupling of small-diameter hose fittings, with two or three small pawls, is not that safe for fittings having a larger diameter.
Another drawback is due to the fact that in large hoses there is a low pressure and a high delivery, so that constricting the cross-section is particularly undesirable; with the usual fittings for small hoses, transformed into large fittings, there would be a constriction at the point where the hose is connected, and another constriction at the entrance of the male element.
Lastly, there exists a considerable disproportion between the external dimensions of the fitting and the actual internal cross-section available for the passage of the fluid, which would be substantially reduced.